robeets



(No Model.) l

- W. S. DE L. ROBERTS 8u J. S. MOLLISON.- THERMO ELECTRIC GENERATOR.l

No. 412,669. K Patent/ed Oct. 8, 1889.

A F/a .To all whom it may concern.:

.UNITED STATES PATENT OFFICE.

\VIL LIAM S. DE L. ROBERTS AND JAMES SMITH MOLLISON, F SYDNEY, NEW SOUTI I WALES.

THERMoELEcTmc GENERATOR.

SPECIFICATION forming part of Letters Patent No. 412,669, dated October 8, 1889. Application tiled February 9., 1889. Serial No. 299,880. (No model.)

Be it kno'wn that we, WILLIAM SCARLETT DE LISLE ROBERTS and JAMES SMITH MOLLI- SON, subjects of the Queen of Great Britain and Ireland, and residents of Sydney, in the .Colony of New South Wales, have invented `certain new and useful Improvements in At mospheric Thermo-Electric Generators; and

vwe do hereby declare that the following is a full, clear, and exact description of the same. This4 invention relates to certain improve-y f ments in the construction of those thermoelectric generators where thermo electric couples are used.

The first part of our invention consists of a stove or furnace which is surrounded by an vture of ire-clay-and asbestus.

'air-tight hot-air chamber, the outerwalls of which are composed of any suitable non-combustible insulating material, preferably a mix- The couples are so inserted into the insulating-wall that for a portion of their length vthey shall project into the hot-air chamber. t The heat in this chamber is regulated by a pyro safetyvalve fixed in any convenient position in the upper part of the chamber. All risk of overheating the chamber will th us be avoided and a uniform heat imparted to the couples that project within the hot-air chamber.

The invention further relates to a novel form of the thermo-electric couples without any joint or soldering at the junction of the metals. This isetfected during the process of casting by fusing the two metals together. By adopting this mode of forming the couples the inconvenience hitherto experienced from the extra resistance and consequent diminution'of the electric current, due to the loosening of the joint by unequal expansion and contraction of the metals, will entirely cease.

In carrying out the invention a furnace or stove of any convenient form may be employed; but for the generation of a large cur rent of electricity for lighting public buildings orstreets it is preferable to use a long narrow stove, the length being proportional to the size of the furnace. The stove or furnace is surroundedby an airspace, which is inclosed on its outer side by a wall composed of any suitable insulating non-combustible length, for reasonshereiuafter more particularly specified. In order to preventoyerheating in the air-chamber, a pyro safety-valve and pyro-gage of any suitable design are placed at the highest part of the air-chamber. Although no particular design of pyrometer is specified, it is preferable to employ one composed of twometals which expand in different ratios, such as cast-iron and zinc. On the airchamber becoming heated to the limit of safety the pyro safety-valve is so adjusted that the expansion of the zinc or other metal shall lift the pyrQsafety-valve, and thus allow the ovrheated air to escape, while at the same time permitting cold air to ent-er the chamber through a valve placed nearits lowcieney of the apparatus to any perceptible extent, an inletpassage near the lowest part of the airchamber may be kept permanently open. l

In constructing thermo-electric couples the lInode usually adopted hitherto has been to .solder the ends of the elements to the negative and positive connecting-pieces, or to simply cast the ends of the elements onto connecting-pieces composed of such metals as tinned iron or copper.

In making our thermo-electric couples we do not confine ourselves to the use of any particular metal or alloys, but we employ two metals or alloys that melt at diiterent temperatures. The metal or alloy of which the connecting-pieces are formed should melt at a lower temperature than the metal or alloy used for the elements. From experiencewe find that the metal'and alloy that give the best results are malleable zinc for the connecting-pieces and an alloy of antimony and zinc for the elements. In order to thoroughly unite the two parts of the couples, the malleable-zinc connecting-pieces are placed within a mold and the alloy of antimony and zinc cast round them. As the zinc will melt at a slightly-lower temperature than the alloy of antimony and zinc, the malleable zinc will, loo

duriing the process of casting, melt into the alloy, and will thus form one united whole, without joint, and with an alloy at the ends of the elements containing a slight excess of zinc. 4 The couples thus constructed are then placed in a frame, packed with the insulating non-combustible material above referred to,

and placed in the outer wall of the air-chamv air-chamber attached to an ordinary cookl inggrange, so that during the process of cookthe thermo-electric couples,which may be so,

ing the couples may convey the electricity generated to a set of electric accumulatore, and the electricity there stored for subsequent use. l

In the accompanying drawings, Figure l is a section of the form of furnace we propose to employ for medinmand large installations. .l Fig. 2 is a plan of the same. Figs. 3 and 4 show our thermo-electric generator applied to an ordinary cooking-stove, Fig. 3 being a sectional plan, and Fig. 4 an elevation, of the apparatus. Fig. 5 is' a perspective View of the thermo-electric couples.

In Figs, 1 and 2, A represents the' furnace; B, the'hot-air chamber that surrounds it; C C,

arranged as to generate either a large current or great electro-motive force, as required. D is the pyro safety-valve, so arranged as toallow the overheated airto escape; E, the pyrogage, to indicate the rise or fall of temperature within the air-chamber. F is the furnace chimney or uptake." In Figs. 3 and 4, represent-ing a domestic cooking-range,(wh-ich maybe connected with a-set of secondary 'electric accumulators,) I is the re-grate. -K K is the iue area forhe'ating-the oven and the hot-air chamber B. The

thermo-electric couples are shown atM M,

projecting, as before described, a portion of their length into the hot-air chamber B.

vof antimony and zinc, forming at the two ends Fig. 5 islaperspectiveview of -our thermo-' electric couples. The two parts of our therino-electric couples are composed of metals or alloys (see Fig. 5) that melt at different ternperatures. In this view m m are the positive and negative connecting-pieces, composed preferably of. malleable zinc, which melts at a low temperature. 'n 'n are the elements, composed preferably of an alloy of antimony and zinc, which melts 'at a 'much higher temperature than the zinc. The ends of the zinc connecting-pieces are yinserted into a mold and the alloy of antimony and zi roast round them. `The result will be that the zinc ends will partially fuse and combine with the alloy of the elements a second alloy of antimony and zinc, having a slight excess of zinc. The

couples will thus be rendered more effective and durable. t

Having now particularly described and ascertained the nature of our said invention and in what manner the same is to be per- I formed, We declare that what we claim is-jl. In thermo-electric. generators, lthe hotair chamber, in combination with the projecting thermo-electriccouples, the separate inner furnace-chamber, and a heat-regulating valve, substantially as described, and as illustrated in the drawings.

2. In `thermo-electric generators, the combination of the 4hot-air chamber and thermoelectric couples with a pyro safety-valve and pyro-gage, substantially as described, and for the purpose herein set. forth.

3. In 'a thermo-electric generator, a couple composed of two metals or alloys which melt. at different temperatures, cast one upon or about the other, so that the metal or. alloy of which the element is composed shall, while in process of casting, cause the partial fusing of the metal or alloy of which the connecting-pieces are composed, and another alloy be thus formed at the point of union' of the metals oralloys,substantially as described, and for the purpose herein set forth. i

In Witness whereof We have hereunto set ourhands in presence of two Witnesses.

W. S. DE L. ROBERTS.

JAMES SMITH Morrison@v TOO 

